Plunger for the introduction of substances with low vaporization temperature into liquid melts



W O L .H Tm T.L wm m Cm mw T su O EWI B Gwm NITb IIT e LWmF KDPd HmTiINF O I mw RI O Fw P mw G m P Oct. 15, 1957 INVENTOR.

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United States Patent PLUNGER FOR THE INTRODUCTION 0F SUB- STANCES WITHLOWVAPORIZATION TEMPER- ATURE INTO LIQUID MELTS Herbert Klingbeil,Dortmund, Germany, assignor to The International Nickel Company, Inc.,New York, N. Y., a corporation of Delaware Application February 1, 1956,Serial No. 562,880 Claims priority, application Germany February 17,1955 8 Claims. (Cl. 75-93) The present invention is directed to an,improvement in an apparatus and in a method for adding reactive agentsto molten metal under pressure and, more particularly` to an improvementin an apparatus and a method for adding to molten metal reactivemetallic agents having a vaporization temperature relatively lower thanthe temperature of the molten metal.

ln my U. S. application Serial No. 445,377, filed July 3, |954 (now U.S. Patent No. 2,776,206, granted January l, l957), I described anapparatus comprising a pressure vessel adapted to hold molten metal, e.g., molten cast iron, and having adapted thereto a lid designed to closethe pressure vessel in a pressure-tight manner and a plunger fastened tothe bottom of said lid adapted to hold addition material and constructedto introduce said addition material below the surface of the moltenmetal held in the pressure vessel practically simultaneously withclosure thereof by said lid so that pressure generated in the closedvessel by vaporization of the addition material in contact with themolten metal is retained in the vessel.

lt is an object of the present invention to provide an improved plungeradapted for introducing reactive addition agents into molten metal inaccordance with the method and apparatus disclosed in my earlier U. S.application Serial No. 445,377 (now U. S. Patent No. 2,776,- 206,granted January l, 1957).

1t is a further object of the invention to provide an improved processwherein solid reactive addition agents may be added to molten metal.

Broadly stated, the plunger contemplated in accordance with the presentinvention comprises' a carrier adapted to be detachably connected to thelid of the pressure vessel described in my earlier application SerialNo. 445,377 (now U. S. Patent No. 2,776,206, granted January 1, 1957).The free end of the said carrier is adapted to have attached theretopieces of the addition material, e. g., magnesium, contemplated to beused in treating molten metal held in the pressure vessel, e. g., moltencast iron. The said carrier and the pieces of addition material attachedthereto are surrounded or covered by a refractory heat insulatingsheath, the wall thickness of which, in the region of the additionmaterial, is great enough to delay melting thereof but not to preventsuch melting. The refractory sheath is preferably produced from aplastic refractory material such as a ramming mix which is usual for thelining of cupola furnaces, crucibles, etc. The addition materialpreferably is first attached ot the carrier and the carrier and theaddition material are then covered with the refractory ramming mix whichadheres strohgly to the assemly after drying.

Embodiments of theI invention are shown in the accompanying drawings.Figures 1 and 2 show in section and cross section a plunger comprising acarrier-andaddition-material assembly which is covered by an insulatingrefractory ramming mix while Figures 3 and 4 show in section and crosssection a earrier-and-additioniCC material assembly in which the carrierhas an insulation of ceramic material or graphite and in which theassembly is covered with a refractory ramming mix. In the embodimentdepicted by Figures l and 2, a tubular carrier body 1 is fitted on theperiphery with a plurality of perforated ribs 2. The carrier is provided`with a bolt 3 on one end which is adapted to fasten the carrier to thelid of the pressure vessel. At the other end, the carrier is providedwith fastening means 4, which can be a nut, for attaching to the carriershaped pieces 5 of the addition material. In the production of cast ironcontaining spheroidal graphite, the shaped pieces or bodies 5 shown inFigures 1 and 3 would consist of magnesium or a magnesium alloy. Theshaped pieces or bodies 5 are provided with a central cast-in carrierrod 6 which may be made of iron or other suitable metal. The rod 6 isadapted to be fixed securely to the carrier 1 by the fastening means 4.

After attaching the pieces of addition metal 5, which can be of anyshape, to the carrier 1, the plunger is sheathed with a refractoryramming mix so that the assembly has a cylindrical form. The function ofthe ribs 2 is to reinforce and secure theramming mix to the carrier. Thewall thickness of the ramming mix is such that in the region of thecarrier 1 it protects the carrier from being melted on immersion intomolten cast iron. 1n the region of the shaped pieces of addition metal5, the wall thickness of the sheath is, however, not enough to preventthe melting of the shaped pieces of addition material, e. g., magnesium,but only to delay such melting until the plunger assembly has beenintroduced into the melt and the lid carrying the plunger has been puttightly on to the opening ot' the pressure vessel.

Preferably, the metallic addition'material 5 is provided in a conicalfrustrum shape such that when the pieces of addition material arefastened to the carrier 1 and are then covered with an envelope ofrefractory ramming mix the wall thickness of the envelope decreasestoward the tree end of the addition material. By this means, the shapeis induced to begin melting at the free end, whereupon it bursts dieenvelope or reiiactory ramming mix and then melts progressively alongits length. 1n this manner, the addition material is prevented fromcoming tree of the plunger prematurely, a circumstance which wouldresult in the addition material rising to the surtace of the melt atwhich point intimate alioying of the audition material with the wholemelt could no longer oe assured. it will ue appreciated trom rigores land 3 that the bottom end of the shaped bodies of addition material 5 1salso covered by the refractory ramming mix. 'the preferred embodiment ofthe invention advantageously can he carried i'nto practice by arrangingthe conical irustrum shape so that it presents its smaller circularsurface to the carrier 1. when this shape is provided with a cylindricalenvelope, the wall thickness of the envelope decreases toward the freeend of the plunger in the region ot the shapes.

ine eiiioodiment according to Figures 3 and 4 depicts a ceramic sheath 9about the central shaft 8. This ceramic sheath may be made of porcelain,burnt clay, electrode carbon, etc. such as depicted in Figures 3 and 4can be used repeatedly and saves the application of large amounts oframming mix in the region of the carrier rod 8.

lhose skilled in the art will appreciate that plastic refractory rammingmixes used in lining cupola fui'- naces and the like may be composed ofvarious mixtures of silica and clay. Mixtures incorporatinggranularmagnesite or dolomite may also be employed where a basicmaterial is preferred. Plastic refractory ramming mixes are described inthe book The Cupola and The sheath of ceramic material 9v Its Operation,second edition, 1954, American Foundrymens Society, for example, atpages 27\ to 29..

It is to be observed that the present invention provides an apparatusand a method for introducing a relatively volatile addition agent intomolten metal. When introducing the addition agent into the molten.metaln lthe plunger consisting of the carrier with the solid additionmaterial afxed thereto, both being coated with the refractory heatinsulating sheath, is attached to the inside surface of the lid of thepressure vessel in the manner hereinbefore described. When the moltenmetal is ready to be treated withthe addition material, the lid ispositioned to close the pressure vessel m a pressuretight manner whileimmersing at least the free end of the plunger in the molten metal. Ashereinbefore described, the heat of the molten metal causes the additionagent to melt, vaporize and burst the ceramic envelope after a shorttime, thus permitting the pressure vessel to be tightly closed prior tothe release of the addition agent, e. g., magnesium. The pressure vesselprevents the escape of the addition material by volatilization andallows the molten metal to absorb the addition material. Preferably, theplunger consists of the carrier and a conical frustrum of additionmaterial attached to the carrier at the smaller circular surface. Acylindrical refractory heat-insulating sheath covers both the additionmaterial and the carrier in the manner described hereinbefore.

Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resoited to without departing from the spirit andscope of the invention, as those skilled in the art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the invention and appended claims.

I claim:

1. In an apparatus adapted for the treatment of molten metal underpressure and comprising a pressure vessel having a lidadapted to closesaid vessel in pressure-tight relation, said lid having connectedthereto a plunger adapted to hold addition 'material on the free endthereof and to insert said addition material into molten metal held insaid vessel when said lid is in pressure-tight relation to said vessel,the improvement which comprises a plunger having a carrier portionadapted to be detachably connected to the pressure vessel lid andaddition material attached to the free end of said carrier, said plungerbeing coated by a layer of refractory heat insulating material providinga substantially cylindrical form to the coated plunger and said layerhaving a wall thickness decreasing toward the free end of the plunger inthe region of the addition material.

2. In an apparatus adapted for the treatment of molten metal underpressure and comprising a pressure vessel having a lid adapted to closesaid vessel in pressuretight relation, said lid having connected theretoa plunger adapted to hold addition material on the free end thereof andto insert said addition material into molten metal held in said vesselwhen said lid is in pressure-tight relation to said vessel, theimprovement which comprises a plunger having a carrier portion adaptedto be de- 'tachably connected to the pressure vessel lid and a conicalfrustrum shaped piece of addition material attached at the smallercircular face of said conical frustrum to the free end of said carrier,said plunger being surrounded by a substantially cylindrical layer ofrefractory heat insulating material having a wall thickness decreasingtoward the free end of the plunger in the region of the additionmaterial.

3. In an apparatus adapted for the treatment of molten metal underpressure and comprising a pressure vessel having a lid adapted to closesaid vessel in pressure-tight relation, said lid having connectedthereto la plunger adapted to hold addition material on the free endthereof and to insert said addition material into molten metal held insaid vessel when said lid is in pressure-tight relation to said vessel,the improvement which comprises a plunger having a carrier portionadapted to be detachably connected to the pressure vessel lid and aconical frustrum shaped piece of addition material attached at thesmaller circular face of said conical frustrum to the free` end of saidcarrier, said plunger being surrounded by a layer of refractory heatinsulating material providing a substantially cylindrical form to thecoated plunger and thereby providing decreasing wall thickness of saidrefractory heat insulating material toward the free end of the plungerin the region of the addition material.

4. In an apparatus adapted for the treatment of molten metal underpressure and comprising a pressure vessel having a lid adapted to closesaid vessel in pressure-tight relation, said lid having connectedthereto a plunger adapted -to hold addition material on the free endthereof and to insert said addition material into molten metal held insaid vessel when said lid is in pressure-tight relation to said vessel,the improvement which comprises a plunger having a carrier partionadapted to be detachably connected to the pressure vessel lid and aconical frustum shaped piece of addition material selected from thegroup consisting of magnesium and magnesium alloys attached at thesmaller circular face of said conical frustum to the free end of saidcarrier, said plunger being surrounded by a layer of refractory heatinsulating material providing a substantially cylindrical contourthereto and thereby providing decreasing wall thickness of saidrefractory heat insulating material toward the free end of the plunger.

5. In the process of adding reactive addition agents to molten metalunder pressure, the improvement which comprises attaching a conicalfrustum shaped piece addition material to a carrier to form a plungerhaving the addition material affixed to one end thereof, said additionmaterial being adapted to melt and vaporize in contact with said moltenmetal, enclosing said plunger in a heat insulating refractory sheathhaving decreasing wall thickness toward said end in the region of theaddition material, aflxing said sheathed plunger to the inside face of alid of a pressure vessel containing molten metal in metal contained insaid pressure vessel while simultaneously closing said vessel in apressure-tight manner to hold therein pressure produced by melting 'saidaddition material.

6. In the process of adding reactive addition agents to molten metalunder pressure, the improvement which comprises attaching a conicalfrustum shaped piece of addition. material to a carrier to form aplunger having said pressure vessel while simultaneously closing saidvessel in a pressure-tight manner to hold therein pressure produced bymelting said addition material.

7. In the process of adding reactive addition agents to molten cast ironunder pressure, the improvement which comprises attaching a conicalfrustum shaped piece of addition material to a carrier to form a plungerhaving the addition material aliixed to one end thereof, said additionmaterial being adapted to melt and vaporize in contact with said moltencast iron, enclosing said plunger in a substantially cylindrical heatinsulating refractory sheath having a decreasing wall thickness towardsaid end in the region of the addition material, aflixing said sheathedplunger to the inside face of a lid of a pressure vessel containingmolten cast iron in such manner that the addition material is positionedat the free end of said sheathed plunger, and imersing at least the freeend of said sheathed plunger in molten cast iron contained in saidpressure vessel while simultaneously closing said vessel in apressure-tight manner to hold therein pressure produced by melting said-addition material.

8. In the process of adding magnesium to molten cast iron to producecast iron under pressure containing spheroidal graphite,the improvementwhich comprises attaching a conical frustum shaped piece of additionmaterial selected from a group consisting of magnesium and magnesiumalloys to a carrier to form a plunger having 4said addition materialaixe'd to one end thereof, enclosing said plunger in a substantiallycylindrical heat insulating refractory sheath to provide a decreasingwall thickness in said sheath toward said end in the region of theaddition material, aiiixing said sheathed plunger to the inside face ofa lid of a pressure vessel containing molten cast iron in such mannerthat the addition material is positioned at the free endof said sheathedplunger, and closing said vessel while immersing at least the free endof said sheathed plunger in molten cast iron contained in the pressurevessel, whereby the release of magnesium is delayed until after the lidhas tightly closed said pressure vessel.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN AN APPARATUS ADAPTED FOR THE TREAMENT OF MOLTEN METAL UNDERPRESSURE AND COMPRISING A PRESSURE VESSEL HAVING A LID ADAPTED TO CLOSESAID VESSEL IN PRESSURE-TIGHT RELATION, SAID LID HAVING CONNECTEDTHERETOA PLUNGER ADAPTED TO HOLD ADDITION MATERIAL ON THE FREE END THEREOF ANDTO INSERT SAID ADDITION MATERIAL INTO MOLTEN METAL HELD IN SAID VESSELWHEN SAID LID IS IN PRESSURE-TIGHT RELATION TO SAID VESSEL, THEIMPROVEMENT WHICH COMPRISES A PLUNGER HAVING A CARRIER PORTION ADAPTEDTO BE DETACHABLY CONNECTED TO THE PRESSURE VESSEL LID AND ADDITIONMATERIAL ATTACHED TO THE FREE END OF SAID CARRIER, SAID PLUNGER BEINGCOATED BY A LAYER OF REFRACTORY HEAT INSULATING MATERIAL PROVIDING ASUBSTANTIALLY CYLINDRICAL FORM TO THE COATED PLUNGER AND SAID LAYERHAVING A WALL THICKNESS DECREASING TOWARD THE FREE END OF THE PLUNGER INTHE REGION OF THE ADDITION MATERIAL.